AWG to mm² Wire Gauge Converter

Convert American Wire Gauge (AWG) to square millimeters (mm²). Calculate bare conductor diameter, ohmic resistance per km and IEC metric equivalent.

Select AWG Wire Gauge

Exact Area (mm²)3.31 mm²

Standard Metric (IEC)4.0 mm²

Conductor Diameter2.05 mm

DC Resistance (Copper)5.21 Ω/km

Mathematical Formula of the ASTM B258 AWG Scale

Standard Reference (ASTM B258 & IEC 60228): North American wire gauges follow a logarithmic geometric progression where every 3 AWG step doubles the cross-sectional area.

Diameter (mm): d_n = 0.127 × 92 ^ ((36 - n) / 39)
Cross-Section (mm²): S_n = (π / 4) × d_n² = 0.012668 × 92 ^ ((36 - n) / 19.5)

Complete AWG to mm² Conversion & NEC 75°C Ampacity Table

AWG Gauge	Exact Area (mm²)	European Metric Size	Diámetro (mm)	Max Ampacity (75°C NEC)
18 AWG	0.823 mm²	1.0 mm²	1.024 mm	7 A - 10 A
16 AWG	1.31 mm²	1.5 mm²	1.291 mm	13 A
14 AWG	2.08 mm²	2.5 mm²	1.628 mm	15 A - 20 A
12 AWG	3.31 mm²	4.0 mm²	2.053 mm	20 A - 25 A
10 AWG	5.26 mm²	6.0 mm²	2.588 mm	30 A - 35 A
8 AWG	8.37 mm²	10.0 mm²	3.264 mm	50 A
6 AWG	13.30 mm²	16.0 mm²	4.115 mm	65 A
4 AWG	21.15 mm²	25.0 mm²	5.189 mm	85 A
2 AWG	33.62 mm²	35.0 mm²	6.544 mm	115 A
1/0 AWG	53.49 mm²	50.0 / 70.0 mm²	8.252 mm	150 A

Frequently Asked Technical Questions (FAQ)

How do you convert AWG wire gauge to square millimeters (mm²)?

Under ASTM B258, conductor diameter in mm is d = 0.127 × 92^((36 - AWG)/39), and cross-sectional area is A (mm²) = (π / 4) × d².

What metric wire size in mm² replaces 12 AWG and 10 AWG?

12 AWG (3.31 mm²) should be replaced with 4 mm² metric wire, and 10 AWG (5.26 mm²) with 6 mm² metric wire.